Abstract

This study provides a deeper insight into the chemistry and physics of the common engineering practice of using a proximity cap, while annealing compound semiconductors such as GaAs. We have studied the cases of a GaAs proximity cap, a Si proximity cap, and no proximity cap. Using x-ray photoelectron spectroscopy, it has been found that annealing increases the gallium to arsenic ratio in the oxide layer in all cases. During the annealing of UV-ozone oxidizedGaAs, it has been observed that GaAs proximity caps also serve as a sacrificial layer to accelerate the desorption of oxide species. In all cases surface deterioration due to pit formation has been observed, and the depth of pits is found to depend on the effective role played by the capping material. Energy dispersive x-ray analysis provides additional evidence that pits mainly consist of elemental As and gallium oxide, with most of the elemental As situated at the pit-substrate interface. Deposition of a thin layer of gold and subsequent annealing to for under different capping conditions shows the use of a proximate cap to be practically insignificant in annealingAu deposited films.

Received 19 March 2007Accepted 27 March 2007Published online 14 June 2007

Acknowledgments:

The authors would like to thank Vanessa Mazzetti and Fred Pearson for their help with the TEM studies. The authors also thank Mark Greiner for helpful discussions. Financial support was provided by the Natural Sciences and Engineering Research Council of Canada through the Discovery Grant Program.